Linerless labels are being increasingly popular because of the environmental advantages associated therewith, and for other operative advantages. However, there have been significant difficulties in producing fully functional linerless thermal transfer labels because a functional printable release material has not been successfully developed. According to the present invention it is possible to provide a linerless thermal transfer label by--instead of using a printable release material--leaving a conventional thermal transfer coating exposed and unaltered, and providing the adhesive and adhesive release material in a pattern to provide a fully functional label while at the same time not interfering with the thermal transfer function.
According to one aspect of the present invention a method of producing linerless thermal labels from a web of thermal transfer base stock having a first face with a thermal transfer coating thereon, and a second face, is provided. The method may be practiced in one pass on a Webtron 1600, or a like printing press, or other conventional equipment, and comprises the steps of: (a) Moving the web in a first direction; while the web is moving in the first direction. (b) Applying spaced patterns of adhesive release material to the first face substantially along the first direction and covering less than 50% of the first face. And (c) applying spaced patterns of adhesive to the second face substantially along the first direction, and substantially in alignment with the patterns of adhesive release material, and covering less than 50% of the second face. The method may also comprise the further step of forming perforations in the web substantially perpendicular to the first direction to define distinct labels in the first direction. The web may be at least two labels wide, in which case there is the further step of slitting the web along the first direction at the patterns of adhesive and adhesive release material, into label webs one label wide. The label web or webs are preferably taken up into rolls, although they may be cut or burst into individual labels, or strips containing a plurality of labels, each strip preferably one label wide.
There may also be the further step, before steps (b) and (c), of imaging registration marks on the first face with ink (as by utilizing conventional flexo technology). The ink--which preferably is dark--may be recognized by sensors or operators to facilitate proper alignment and application of the adhesive release material patterns and/or the perforations.
Steps (b) and (c) are typically practiced to apply the patterns as substantially continuous strips along edges extending in the first direction of individual labels, and so that the adhesive release material patterns are slightly wider than the adhesive patterns. Step (b) may be practiced by applying UV curable silicone release material on substantially continuous strips, and in that case there is the further step (substantially immediately after step (b)) of (d) of UV curing the silicone release material. Step (c) may be practiced after step (d) and by applying hot melt permanent adhesive.
According to another aspect of the present invention a linerless label is provided comprising the following components: A substrate of label material having first and second faces, each face having first and second substantially parallel first and second edges. A coating of thermal transfer material substantially completely covering the first face. First and second adhesive release material patterns disposed substantially along the first and second edges of the first face. The first and second adhesive release material patterns having first and second width dimensions in a direction perpendicular to the first and second edges. And first and second adhesive patterns disposed substantially along the first and second edges of the second face in alignment with the first and second adhesive release material patterns, respectively, the first and second adhesive patterns having third and fourth width dimensions, respectively, in a direction perpendicular to the first and second edges, the third and fourth widths not being significantly greater than the first and second widths, respectively.
The third and fourth dimensions are less than the first and second width dimensions, respectively, in the preferred embodiment, and the first and second width dimensions are typically substantially equal to each other, while the third and fourth width dimensions are also substantially equal to each other. The adhesive release material and adhesive patterns may both comprise substantially continuous strips; a preferred material for the adhesive release material is a UV curable silicone, while the preferred material for the adhesive is a hot melt permanent adhesive.
The linerless label may also further comprise ink registration marks imaged on the first face for registration of adhesive release material and/or perforation application. The linerless label may be in combination with a plurality of like labels, with perforation lines extending generally transverse to the first and second edges distinguishing the labels from each other.
It is the primary object of the present invention to provide an effective linerless thermal transfer label, and a method of manufacture thereof. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.